Comparison with 1861 |
|
suppose that their common progenitor had an upper lip, mandibles, and two pair
of maxillæ, these parts being perhaps very simple in form; and then natural selection
will
account for the infinite diversity in structure
and function
of the mouths of insects. Nevertheless, it is conceivable that the general pattern of an organ might become so much obscured as to be finally lost, by the atrophy
and ultimately by the complete abortion of certain parts, by the soldering together
of other parts, and by the doubling or multiplication of others,—
varia- tions varia- tions 1861 | variations 1859 1860 1866 1869 1872 |
which we know to be within the limits of possibility. In the paddles of the extinct gigantic
sea-lizards, and in the mouths of certain suctorial crustaceans, the general pattern seems to have been
thus to a certain extent
obscured. |
|
There is another and equally curious branch of the present
subject; namely, the comparison not
of the same
part
in different members of a class, but
of the different
parts or organs in the same individual. Most physiologists believe that the bones of the skull are homologous with—
that is
correspond in number and in relative connexion with—
the
elemental parts of a certain number of vertebræ. The anterior and posterior limbs in each member of the vertebrate and articulate
classes are plainly homologous. We see the same law in comparing
the wonderfully complex jaws and legs in
crustaceans. It is familiar to almost every one, that in a flower the relative position of the sepals, petals, stamens, and pistils, as well as their intimate structure, are intelligible on the view that they consist of metamorphosed leaves, arranged in a spire. In monstrous plants, we often get direct evidence of the possibility of one organ being transformed into another; and we can actually see
in embryonic crustaceans and in many other animals, and in flowers,
that
organs, which when mature
|
suppose that their common progenitor had an upper lip, mandibles, and two
pair pair 1859 1860 1861 1866 1869 | pairs 1872 |
of maxillæ, these parts being perhaps very simple in form; and then natural
selection selection 1859 1861 1866 1869 1872 | selection, 1860 |
will will 1859 1861 1866 1869 1872 |
acting on some originally created form, will 1860 |
account for the infinite diversity in
structure structure 1859 1860 1861 1866 | the structure 1869 1872 |
and
function function 1859 1860 1861 1866 | functions 1869 1872 |
of the mouths of insects. Nevertheless, it is conceivable that the general pattern of an organ might become so much obscured as to be finally lost, by the
atrophy atrophy 1859 1860 1861 1866 | reduction 1869 1872 |
and ultimately by the complete abortion of certain parts, by the
soldering together soldering together 1859 1860 1861 1866 | fusion 1869 1872 |
of other parts, and by the doubling or multiplication of others,—
variations variations 1859 1860 1866 1869 1872 | varia- tions 1861 |
which we know to be within the limits of possibility. In the paddles of the
extinct gigantic extinct gigantic 1859 1860 1861 1866 | gigantic extinct 1869 1872 |
sea-lizards, and in the mouths of certain suctorial crustaceans, the general pattern seems
to have been to have been 1859 1860 1861 1866 |
OMIT 1869 1872 |
thus to
a certain extent a certain extent 1859 1860 1861 1866 |
have been partially 1869 |
have become partially 1872 |
obscured. |
|
There is another and equally curious branch of
the present the present 1859 1860 1861 1866 | our present 1869 | our 1872 |
subject; namely,
the comparison not the comparison not 1859 1860 1861 1866 1869 |
serial homologies, or the comparison 1872 |
of the
same same 1859 1860 1861 1866 1869 | different 1872 |
part part 1859 1860 1861 1866 | parts 1869 1872 |
in different members of a class, but in different members of a class, but 1859 1860 1861 |
or organ in different members of the same class, but 1866 |
or organs in different members of the same class, but 1869 |
or organs in the same individual, and not 1872 |
of the
different different 1859 1860 1861 1866 1869 | same 1872 |
parts or organs in
the same individual. the same individual. 1859 1860 1861 1866 1869 |
different members of the same class. 1872 |
Most physiologists believe that the bones of the skull are
homologous with— homologous with— 1859 1860 1861 1866 1869 | homologous— 1872 |
that
is is 1859 1860 1861 | is, 1866 1869 1872 |
correspond in number and in relative
connexion with— connexion with— 1859 1860 1861 1866 1869 | connexion— 1872 |
the the 1859 1860 1861 1866 1869 | with the 1872 |
elemental parts of a certain number of vertebræ. The anterior and posterior limbs in
each member of the vertebrate and articulate each member of the vertebrate and articulate 1859 1860 1861 |
all the members of the vertebrate 1866 |
all the higher vertebrate 1869 1872 |
classes are plainly homologous.
We see the same law in comparing We see the same law in comparing 1859 1860 1861 |
So it is with 1866 1869 1872 |
the wonderfully complex jaws and legs
in in 1859 1860 1861 | of 1866 1869 1872 |
crustaceans. It is familiar to almost every one, that in a flower the relative position of the sepals, petals, stamens, and pistils, as well as their intimate structure, are intelligible on the view that they consist of metamorphosed leaves, arranged in a spire. In monstrous plants, we often get direct evidence of the possibility of one organ being transformed into another; and we can actually
see see 1859 1860 1861 1866 | see, 1869 1872 |
in embryonic crustaceans and in many other animals, and in flowers, in embryonic crustaceans and in many other animals, and in flowers, 1859 1860 1861 |
in flowers during their early development, as well as in crustaceans and many other animals during their embryonic states, 1866 |
during the early or embryonic stages of development in flowers, 1869 1872 |
that that 1859 1860 1861 1866 |
as well as in crustaceans and many other animals, that 1869 1872 |
organs, which when mature
|